1. Field of the Invention
The invention relates to an electrical heating means for cookers and hot plates having a heat-resistant support disposed below a heat-radiation transmitting plate, in particular a glass-ceramic plate, said support member being adapted to receive at least one electric heater filament.
2. Description of the Prior Art
Electric cookers equipped with so-called "radiation hot plates" are being used to an increasing extent. Their cooker surfaces are formed, for example, by a glass plate. Circular, square or rectangular electrical heating means, usually of different sizes, are disposed below the glass plate. The heat produced by the electrical heating means is transmitted mainly by radiation onto cooking or frying vessels placed onto the glass plate.
Examples of embodiment are known, wherein the heater filament producing the heat is placed at a definite distance from the lower side of the glass plate. A shell-shaped structure made of a heat-resistant material is secured to the lower side of the glass plate. The heater filament is placed into the bottom of the shell-shaped structure. These embodiments provide the advantage that the glass plate is not subjected directly to the relatively high temperature of the heater filament and that each heater filament irradiates a large section of the glass plate, because of the widening of the radiation cone. In this way the radiation passing through the glass plate is thus distributed. It is a disadvantage of these embodiments, however, that a relatively high proportion of the heat energy produced by the heater filament is conducted away in downward direction and therefore becomes lost. These losses adversely affect the energy requirements and, furthermore, the heater filament or spiral must be heated to a high temperature in order that the required heating power may be transferred to the cooking or frying vessel positioned on the hot plate. This high temperature appreciably shortens the life of the heater filament.